VEXTEC Reliability Analysis of Above-the-Knee Leg Prosthesis

1. VEXTECReliability Analysis of Above-the-Knee Leg Prosthesis Group 11 Aashish Bapat, April Boldt, Jason Deaner, Grainger Greene, Dani Shuck

2. Company Overview • VEXTEC’s reliability analysis capabilities: • Unique approach with usage of ‘physics of failure’ and ‘material science libraries’ • Funded by a Federal government grant • Competitors tools are limited as they only use statistical analysis • Current Customers: Aerospace & Automotive markets • Goal:Break into the Medical Device Sector

3. Reliability Analysis Technology Overview • Desktop Computational Reliability Model (DCRM) • Predicts fatigue failure • Simulates real material degradation models • How it works? • Grain structure of materials given conditions • Monte Carlo Probabilistic methods • Modeling of this early crack behavior • 3D Component Analysis

4. Project Goals • Predict reliability of above-the-knee prosthetic leg (Finite element analysis) • Material • Geometrical • Loading • Available data on failure • Modify the design of Reliability analysis software for the prosthetic leg

5. Project Goals (contd.) • Market Analysis • Potential Medical device manufactures • Testing cost and time reduction analysis • Meetings with the medical device industry to identify specific market needs • Aid for FDA approval • FDA • Potential tool for the FDA to run preliminary design reliability analysis

6. Division of Work • Dani: Prosthesis model, Team Leader • Aashish: Biomechanics • Jason: MSC/PATRAN modeling, Finite Element Analysis • Grainger: Medical device market research, manufacturing and professional contacts • April: Manufacturing and professional contacts

7. Prosthetic Leg analysis • Journal of Rehabilitation Research & Development • Prosthetic Loading during kneeling • Blatchford Manual Lock system for K1 – K2 activities • 162 tests in prosthetic knee undertaken • Critical Shear Forces and stress measure with sensors

8. Modeling the knee Unit • Fatigue failure often observed at the Knee Unit • Knee unit isolated and modeled • Reliability analysis on three pins shown in the socket • Once set up, similar analysis can be performed on the whole prosthesis to determine reliability PSP Endo Stabilised Knee with Manual Knee Lock

9. Knee socket model 3 D model built in Pro/Engineer PSP Endo Stabilised Knee with Manual Knee Lock

10. Assessing the reliability of the Knee Unit • A 2-dimensional projection of the simplified ankle joint will be analyzed in MSC/Patran with MSC/Nastran or ANSYS. • The results will be used in VPS-MICRO to analyze the microstructure. • The goal is to see what VEXTEC’s software can add to the medical industry’s current analysis techniques.

11. Medical Trade Shows • Cannon Communications LLC: leader of trade show publications for medical manufacturing • MEDTEC Germany (Messe Stuttgart, Germany, Feb 27-March 1, 2007) • MD&M East (New York, NY, June 12-14, 2007) • MEDTEC China (Shanghai, China August 28-30, 2007) • MEDTEC Ireland (Galway, Ireland, September 19-20, 2007) • BIOMEDevice (MD&M Event, San Jose, CA, October 3-4, 2007) • MD&M Minneapolis (Minneapolis, MN, October 17-18, 2007) • MD&M West (Anaheim, CA, January 29-31, 2008) • Medical Device and Manufacturing Trade Shows: • Sponsored by Medical Device and Diagnositc Industry http://www.devicelink.com/mddi/

12. Medical Trade Shows • Medical Design & Manufacturing West • January 28-31, 2008 • Anaheim Convention Center, CA • Large-scale tradeshow, 1500 exhibiting companies in the $104 Billion medical device market • Suppliers in cardiovascular, orthopedics, prostheses, etc. • Medical Design & Manufacturing East • June 11-14, 2007 • Jacob K. Javits Convention Center, New York City • Mid-size tradeshow • Pharma Med Device • April 24-26, 2007 • Jacob K. Javits Convention Center, New York City • Over4,000 pharmaceutical and medical device manufacturers • Will look for more advice from Dr. Watson and other contacts

13. Interview with Dr. Fitzsimmons • Easier to get devices approved in Europe • ISO standards less than FDA • Perform physical tests with predetermined forces • Warranties are mostly guesswork • Feet – 36 months • Knee – 24 to 36 months • Medicare recommends 5 year life for prosthesis • Ultimately depends on activity level (0-4) • 4 level cannot expect for device to last more than a year • Most failures from feet • Below-the-knee prostheses more common than above-the-knee, thus more feet likely to fail than knee’s

14. Interview with Dr. Fitzsimmons • List of manufacturers • Otto Bock • Ossur • Endolite • Ohio Willowood • Medi • Bulldog Tools • Jim Smith Sales • Euro International • Fillauer • Otto Bock has 4-5 large facilities within U.S. • Provided contact with Otto Bock

15. Phone Call to Otto Bock • Spoke with Scott Weber, Marketing Manager for Feet Units at Otto Bock Minneapolis office • Most prostheses exempt from FDA approval, use ISO standards • Microprocessor knee unit is not FDA exempt • Physical testing is expensive and time consuming, lots of money wasted on testing incorrect prototypes • Exo-skeletal knee prostheses are vanishing from market • Feet units are more customized than Knee units, more failures in them also

16. Phone Call to Otto Bock (contd.) • They do use Finite Element Analysis to some extent in their reliability analysis • Do not use statistical modeling, never heard of Relex or Reliasoft • Otto Bock goes above and beyond ISO standards in their testing • ISO would be a good resource for specific force loads used on prosthesis units. • Gave contact at Salt Lake City office • Sarah McCarviell, Head Engineer(?) • All physical testing and design engineering done at Salt Lake City office

17. Future Work: • Use VEXTEC’s VPS-MICRO software to perform analysis on knee joint for kneeling forces • Perform same analysis on same device for walking forces • Speak with design engineers at different prostheses manufacturers about applicability of VEXTEC’s technology • Speak with FDA Compliance Consultants about possible FDA usage/acceptance

18. Resources • http://www.devicelink.com/expo/west07/ • http://www.devicelink.com/mddi/ • http://www.pharmameddevice.com/